The Russian-American lobbyist who attended a meeting at Trump Tower last year is a former military officer who has attracted congressional scrutiny over his political activities.

Rinat Akhmetshin has also been shadowed by allegations of connections to Russian intelligence that he denies.

Mr Akhmetshin confirmed his participation in the meeting on Friday, providing new details of a June 2016 sit-down that included a Russian lawyer and President Donald Trump’s oldest son, son-in-law and campaign chairman.

His attendance at the meeting and his lobbying background created a new wrinkle to a story that has hounded the White House for days and added to questions about potential coordination between Russia and the Trump campaign.

Mr Akhmetshin is well-known in Washington for his advocacy efforts.

He has been outspoken in recent years about a US law levying sanctions on Russians and has worked to undermine the public narrative used to justify the bill.

And his name has also surfaced in multiple American lawsuits, including one involving the hacking of a company’s computer systems.

Emails released this week by Donald Trump Jr show the president’s son agreed to the Trump Tower meeting with the idea that he would receive damaging information on Hillary Clinton from someone described to him as a “Russian government attorney”.

Mr Akhmetshin began working with that lawyer, Natalia Veselnitskaya, in 2015, after a public relations person he declined to name introduced them.

The Russian government has denied any involvement or knowledge of the meeting.

In an interview, Mr Akhmetshin denied suggestions made in media reports, congressional letters and litigation that he is a former officer in Russia’s military intelligence service known as the GRU, dismissing the allegations as a “smear campaign”.

He said that he served in the Soviet Army from 1986 to 1988 in a unit that was part of counter-intelligence, but he was never formally trained as a spy.

He said his unit operated in the Baltics and was “loosely part of counter-intelligence”.

Mr Akhmetshin, a naturalised American citizen who has lived in Washington since the early 1990s, and Ms Veselnitskaya are known for lobbying efforts involving the Magnitsky Act, a brace of economic sanctions targeting Russian officials and individuals

The act passed by Congress was named after Russian lawyer Sergei Magnitsky, who died in a Russian prison in 2009 after accusing Russian government officials and takeover raiders of a multi-million dollar tax fraud scheme in the seizure of an investment firm.

Early in 2016, Mr Akhmetshin said he helped set up a non-profit foundation based in Delaware to lobby US officials in an effort to strip Mr Magnitsky’s name from the law, though he maintains that he was not attempting to undercut it.

As an adjunct to the foundation’s lobbying, Ms Veselnitskaya also organised and attended a screening of an anti-Magnitsky documentary film that played at the Newseum in Washington four days after she met with Mr Trump Jr in New York.

Mr Akhmetshin acknowledged he was also involved in promoting the film.

Mr Akhmetshin said he has not been contacted by the special counsel’s office or the FBI about the meeting with Mr Trump Jr.

He said he is willing to talk with the Senate Judiciary Committee, whose chairman has pressed the Justice Department about why Mr Akhmetshin has not registered as a foreign agent.